PSI - Issue 36

Mykhailo Hud et al. / Procedia Structural Integrity 36 (2022) 79–86 Mykhailo Hud / Structural Integrity Procedia 00 (2021) 000 – 000

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hydrodynamic loading; formation of dents in the lower part of the tank body; displacement of the tank body relative to the base; local shrinkage of the base under the bottom of the tank; the total slope of the tank; overturning the tank; lifting of the bottom from the base and damage of the nodes connecting the body with the bottom and the connections of the pipeline. Fundamental research in the field of seismic resistance of tank structures has been conducted both in our country and abroad since the 50s of the twentieth century. For instance, in the studies Malhotra (1997), Veletsos and Yang (1996), there was a transition from the so-called "static theory" to models based on the nature of soil movement, inertial and viscoelastic properties of structures. Peculiarities of seismic reactions of reservoirs containing large volumes of liquid have been studied in detail in basic works by Malhotra et al (1997), Pyndus and Kononchuk (2016). It is the work by Shirt (2018), as well as other publications of J. Hauser and his followers that formed the basis of the calculation ratios included in the relevant sections of the standards API-650, API-620, AWWA D100. The requirements of Eurocode 8 are based on the same principles, which takes into account current trends in the development of construction in seismically dangerous areas. The large share of Eurocode 8 sections on tanks is typical. For storage of light oil products, for example, kerosene and fuel oil with low vapor elasticity, conventional vertical cylindrical tanks of low pressure with a stationary roof (with an excess pressure of up to 2 kPa and a vacuum of up to 0.25 kPa ) are used by Shirt (2018). Crude petroleum products and gasoline with high vapor elasticity are stored in vertical cylindrical tanks with pontoons (Fig. 1) or floating roofs or in high pressure tanks (up to 70 kPa ). Petroleum products and liquefied gases are stored in vertical cylindrical or spherical isothermal tanks at negative temperatures or in horizontal cylindrical and spherical tanks under high internal pressure (up to 1800 kPa ) by Yasniy (2020).

Figure 1. Vertical cylindrical tank with a volume of 50 thousand m with a pontoon: 1-pontoon; 2-pontoon guide tube; 3-spherical roof; 4 mine stairs; 5-closed compartments of the pontoon; 6-pontoon racks; 7-bottom by American Petroleum Institute (2003).

Figure.2. Schemes of destruction of vertical steel cylindrical tanks during an earthquake by American Society of Civil Engineers (1984).

Damage to vertical cylindrical steel tanks caused by strong earthquakes was analyzed. As a result of generalization of data on consequences of earthquakes on reservoirs, it is possible to draw a conclusion that the main reasons of their accidents at seismic influences (Fig. 2) are: failure of the floating roof and damage to the floating roof stairs (Fig. 2a); failure of a stationary roof as a result of impact of a wave of fluctuating liquid (Fig. 2b); loss of stability of the upper part of the body (Fig. 2c); plastic deformations of the shell of the tank in the lower part (the so called "elephant's foot") from the action of hydrodynamic loading (Fig. 2d); formation of dents in the lower part of the tank body (Fig. 2e); rocking of the tank (Fig. 2f); displacement of the tank body relative to the base (Fig. 2g); local shrinkage of the base under the bottom of the tank (Fig. 2h); the total slope of the tank (Fig. 2j); overturning the tank (Fig. 2k); lifting of the bottom from the base and damage of the nodes connecting the body with the bottom and the connections of the pipeline (Fig. 2i). It can be noted that the above damage SVCR as a result of seismic impact is associated not only with the influence of inertial force from the own weight of the liquid, tank and equipment, but also mainly the influence of fluctuating fluid, which depending on the level of tank filling causes hydrodynamic hit the roof and tank body. It should be noted that the need to increase the wall thickness of the SVCR body is usually associated with the